Bacteria in the mouth infects the tissues surrounding teeth, causing gums to become inflamed and painful in periodontal disease. The bacteria forms plaque and then tartar, making teeth harder to clean without professional removal along the gumline. Signs of periodontitis include swollen, bleeding gums; pockets of pus under the gumline; receding gums; bad breath; tooth decay; loose teeth; and pain when chewing. Risk factors include smoking, diabetes, poor oral hygiene, stress, heredity, and certain medical conditions or medications. Treatment involves a professional cleaning to remove plaque and tartar below and above the gumline.